window.onload = init;
window.onresize = adjustHeight;

function init() {
  adjustHeight();
}

function adjustHeight() {

  document.getElementById('main').style.height = 'auto';
  document.getElementById('menu').style.height = 'auto';
  var myWidth = 0, myHeight = 0, blah = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }

  myHeight = myHeight - 25;

 if(document.getElementById('main').offsetHeight < myHeight){
  document.getElementById('main').style.height = myHeight + 'px';
 }
 if(document.getElementById('main').offsetHeight < document.getElementById('menu').offsetHeight){
  blah = document.getElementById('menu').offsetHeight + 2;
  document.getElementById('main').style.height = blah + 'px';
 }
  blah = document.getElementById('main').offsetHeight - 2;
  document.getElementById('menu').style.height = blah + 'px';
}